main, rpcclient, integration: add rpccalls for invalidate and reconsiderblock

[Crypt-iQ]

Adds rpc calls for the invalidate and reconsiderblock methods on BlockChain.

Replaces #2183 and depends on https://github.com/btcsuite/btcd/pull/2196

[coveralls]

Pull Request Test Coverage Report for Build 9423884255

Details

• 144 of 210 (68.57%) changed or added relevant lines in 3 files are covered.
• 15 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.2%) to 57.237%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rpcserver.go	0	26	0.0%
blockchain/chain.go	129	169	76.33%
<!--	Total:	144	210	68.57%	-->

Files with Coverage Reduction	New Missed Lines	%
blockchain/chain.go	3	74.78%
connmgr/connmanager.go	3	86.27%
peer/peer.go	9	74.08%
<!--	Total:	15		-->

Totals
Change from base Build 9348961734:	0.2%
Covered Lines:	29797
Relevant Lines:	52059

---

💛 - Coveralls

[Roasbeef]

Needs a rebase!

[coveralls]

Pull Request Test Coverage Report for Build 9589424465

Details

• 15 of 41 (36.59%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.2%) to 57.249%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rpcserver.go	0	26	0.0%
<!--	Total:	15	41	36.59%	-->

Totals
Change from base Build 9589079505:	0.2%
Covered Lines:	29803
Relevant Lines:	52059

---

💛 - Coveralls